There are 3 sub-menus, using different ways to show biological molecules: On this site I have tried several different ways of displaying molecules in 3 dimensions. A variety of open source programs have been released to enable more general educational use, mostly originating in a program called Rasmol. Some computer programs can display molecular structure in a variety of formats, some of which are commercially protected. This topic has connections with other BioTopics units :.
This basically explains the structure of starch and glycogen. This branching occurs in amylopectin, (a small section of which is shown here): This 3-D branching also produces other points at which glucose may be added by condensation or removed by hydrolysis. On the other hand, 1-6 linkage causes the formation of a branching point which then allows another chain of 1-4 linkages to develop. This is the situation in amylose, (a linear part of which is shown here): The chain of 1-4 linkages so formed can be quite long, and may wind up into a helix. Repeating the condensation process will result in the polysaccharide starch, which is considered to have 2 components, amylose and amylopectin. This numbering is important when glucose units are joined together.ġ-4 linkages (formed by glycosidic bonding) result in a simple linear (end to end) connection, which is found in maltose, a disaccharide:
It is worth knowing the numbers used to describe each of the 6 carbon atoms. Some of the lines may be thickened or flared out to give an impression of 3D structure on the pageĪll the other groups can vary in different hexose sugars, which result in slightly different chemical properties. There are in fact 3 versions of the ring structure called chairs and boat, depending on the bending in or out of the left and right corners, but it is easier to draw it as a flat hexagon. In alpha glucose the -H group of the rightmost Carbon atom (C1) is above the plane of the ring, whereas it projects below the ring in beta glucose. This is because the orientation of these groups slightly alters the chemistry of the molecule, so the resulting molecules are given different names. Sometimes the details of just some of these -H and -OH gr oups are drawn in at one end (or both ends).
These lines represent carbon atoms, and -H and -OH groups, most of which have been left out for simplicity. Note that there is an oxygen atom forming part of the ring, and that there are simple lines drawn making up the rest of the ring, and a section sticking out to one side. In life - in your blood and inside cells of plants and animals - most of the glucose consists of molecules shaped into a ring (actually a 6-sided figure, a hexagon) which may be drawn with this fairly simple format: In some books you may see diagrams of the glucose molecule looking like this: This so-called stick diagram really only describes how things are in dry (powder) glucose. You may wish to know in some detail how these 24 atoms are arranged in the molecule of glucose - the structural formula. Its chemical formula is C 6H 12O 6, and this empirical formula is shared by other sugars - called hexoses - 6 carbon sugars. It is also known as blood sugar, and dextrose. Glucose is an example of a carbohydrate which is commonly encountered. To the right of this page I have put a number of links to other files on this website showing 3-D molecules of carbohydrates, which offer the opportunity to see and interact with these molecular models in 3 dimensions.Īt the bottom of the page there are also links to related topics at this level on the BioTopics website
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